I'm planning on headers and S/Cing my car next spring. I have an A4 so my question is how many of you stayed w/ the 2.73/3.15 and why, also who upgraded to 3.42 and why. Is upgrading to 3.42's worth the extra coin when going FI? I do plan to go to the track occassionally but I do a lot of interstate driving (ie Waldorf, MD to Savannah GA) so I want a happy medium. Thanks in advance guys

 

3:42 is the best all around gear in my opinion as it's strong, has a good amount of pickup, and still maintains good fuel economy..

You'll pick up quite a bit of grunt down low relative to a 2:73, but will lose a small bit of fuel economy as you'll be spinning a little more RPM.

 

3.42!

 

I had 3.90s for a while, which made for instant boost but also a lot of tire smoke. I am now running a 3.73, which I prefer. This seems to be a good all around gear. Personally after running a 3.73, I will not go to a 3.42. Especially with a low compression motor, where you lose a little bit of that instant throttle response.

 

If you have 3.15s you may consider staying with those. 2.73s I would definitely change out for 3.42s or something else. If you plan on running a sticky tire, most which can't be daily driven, then a 3.42 or higher gear even would really be noticeable.

 

3.42 with a 2600 stall PI. converter will give you instant boost off idle with a centrifugal SC.

 

So how much of a different is the 3.42 versus the 2.73's (in the quarter mile). I have heard it is like a .5 stock for stock does the difference increase w/ more mods. I also want to add in the equation that even though it isn't a DD I do make a lot of long distance trips in it.

 

Check ECS web site under gear change that might help you some.

 

I went from 3.15's to 3.42's in my A4 - it is the best gear for the A4 and it totally compliments the SC/FI very well!

I also have a YANK 3200 Stall Converter that really gets the Vette moving and into the power it wants

Thanks,Matt

 

Anything above 3.42 and the tires are going up in smoke. 2.73 won't give you the push off the line. About 3-4 tenths would be the difference between the two ratio's!

 

Everyone thanks for the input. With the answers you all have provided I don't think I am going to go w/ 3.42's. I am not that serious about the track so .4 of a second won't bother me (I just enjoy being able to get up to high speeds and not have to worry about tickets, court cost or revoked driver's license. Also the adrenaline rush of going down the track is a great stress reliever).

 

I have a wimpy 2.59 on my C4 automatic. I was considering increasing the ratio but I really cant hook it up in 1st gear as it stands and I am somewhere about 400RWHP.

What I do like is that at highway speed, you can hammer it and it drops into 2nd gear, right into boost and puls very strongly. For highway driving the lower numerical ratio is really killer, especially for passing gear.

I would expect a supercharged C5 to react even better.

 

I ran my TT C5 with the stock 2.73 for almost 8 months before putting in the 3:42 gears. I've got a 98 C5 A4 bone stock motor with a 7psi STS twin turbo kit (dynojet: 446 rwhp)

I miss a few things about the 2.73s specifically the noise levels while cruising on the freeway are much higher now. The rpm's are up in the range where my lack of mufflers makes more noise in my convertible than I'd like. It would be nice to have a fifth 'gear' to drop in to My mileage is down a few ticks, not a big deal but worth mentioning, I used to see 30mpg cruising long distance at 70mph and now it's around 26. Total average mileage has gone from 24 to 22 (still not bad considering the way I drive it ). And finally, I don't think I can hit 174mph like with the 2.73's

The positives far outweigh the negatives though. I am very very happy that I did change out my gears and I wouldn't hesitate to recommend doing the swap for anyone with 2.73's who has added a FI system to their car. The launch off the line has gone from anemic to entertaining. And the way it gets in to boost and runs through the usual speeds (25-60, 35-80, 65-100) is much quicker than before. Even though it's a 25% increase in tq put to the ground it really feels like more.

The only thing I would suggest weighing would be how important is freeway cruising compared to acceleration for you. It's a trade off one way or the other.

 

I have an A4 and I'm keeping the 3.15s in my car on just under a 28" tire. I'm hoping to make power in the 900+ range. Should still hook when I get the suspension dialed in and will provide the trap speeds I'm looking for eventually.